This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-118640, filed Apr. 17, 2001; and No. 2001-133435, filed Apr. 27, 2001, the entire contents of both of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a variable-profile optical device and optical element in which a curvature can continuously be changed, particularly to a small-sized variable-profile optical device and optical element to which a semiconductor technique is applied.
Moreover, the present invention relates to a variable-profile mirror and variable-profile optical element, particularly to a small-sized variable-profile mirror and variable-profile optical element to which a semiconductor technique is applied in a variable-profile optical device having a curvature able to be continuously varied.
2. Description of the Related Art
In micro optics such as an optical pickup, for the purpose of simplifying a mechanism related with focusing in which an electromagnetic actuator is used, there has heretofore been proposed a micro variable focus mirror in which the curvature of a reflective surface can be changed.
Moreover, also in small-sized optics for camera, application of the variable focus mirror can largely contribute to miniaturization.
In a variable focus mirror, when a so-called micro electromechanical system (MEMS) technique with a semiconductor manufacturing technique applied thereto is used, low-cost high-precision production can be expected.
Known driving methods for this type of variable-profile mirror include using an electrostatic attractive force, as described in Jpn. Pat. Appln. KOKAI Publication No. 2-101402, a piezoelectric effect, as described in Jpn. Pat. Appln. KOKOKU Publication No. 3-81132, fluid pressure, as described in Jpn. Pat. Appln. KOKAI Publication No. 1-219801, and the like.
These methods have advantages and disadvantages, but the method of using fluid pressure is suitable for use in which a relatively large displacement to a convex surface from a concave surface is required.
As an example of a variable-profile mirror driven by fluid pressure, the method described in Jpn. Pat. Appln. KOKAI Publication No. 1-219801 will briefly be described with reference to FIG. 26.
A variable focus mirror 1 is constituted of a shell 2, chamber pressure adjustment apparatus 3, and reflective mirror 4.
A pressure chamber 5 is formed in the shell 2, and a holder 7 for holding the reflective mirror 4 in an airtight manner by O rings 6 is formed in an opening of the shell.
The pressure chamber 5 is connected to a pressure gauge 8 and piping 9 of the chamber pressure adjustment apparatus 3.
The piping 9 is branched into a compressor piping 9a and vacuum pump piping 9b, and the piping can appropriately be switched to a compressor 11a or a vacuum pump 11b by electromagnetic operation valves 10a, 10b. 
In the constitution, the switching is performed, when a controller 12 opens/closes the electromagnetic operation valves 10a, 10b. 
The reflective mirror 4 is formed of a thin plate, and a reflective surface 13 is coated with a reflective material such as aluminum.
In the variable focus mirror 1 constituted as described above, to obtain a concave reflective surface 13a, the electromagnetic operation valve 10a is closed, and the electromagnetic operation valve 10b is opened by the controller 12.
In this case, when the pressure chamber 5 is connected to the vacuum pump piping 9b, a negative pressure is produced by the vacuum pump 11b. 
Therefore, in this case, the reflective mirror 4 is deflected toward the pressure chamber 5, and the concave reflective surface 13a is formed.
On the other hand, to form a convex reflective surface 13b of the reflective mirror 4, the electromagnetic operation valve 10a is opened, and the electromagnetic operation valve 10b is closed by the controller 12.
In this case, when the pressure chamber 5 is connected to the compressor piping 9a, a positive pressure is produced by the compressor 11a. 
Therefore, in this case, the reflective mirror 4 is deflected away from the pressure chamber, and the convex reflective surface 13b is formed.
Furthermore, when the pressure of the pressure chamber 5 is controlled to be the same as an external pressure, the reflective surface 13 has a flat reflective surface 13c due to the elasticity thereof.
For the shape of the reflective surface 13, when the controller 12 is controlled based on a measured value of the pressure gauge 8, the reflective mirror 4 can continuously be set at an optional focal distance.
As compared with the electrostatic attractive force driving method in which the displacement amount is limited by the distance between electrodes, or the piezoelectric driving method in which it is difficult to obtain a large deflection because of limitation of the materials of the reflective surface, the variable-profile mirror whose driving source is fluid pressure is preferable particularly for use in which a broad range of focal distances are required.
The variable focus mirror of the above-described fluid pressure system has a problem that a pump or compressor is necessary and therefore it is very difficult to miniaturize the mirror.
Moreover, the above-described variable focus mirror of the fluid pressure system has complicated mechanisms such as a valve, and has a problem that efficiency or response is deteriorated due to the pump and pressure chamber channel.
Furthermore, since a uniform force is exerted on a deformable portion of the variable focus mirror in principle in the method of using fluid pressure, the deformed shape has rotational symmetry. However, since light is generally incident from an oblique direction in relation to a light path in the reflective optics, a large aberration is generated.
In this respect, the transmission type variable-profile optical device (i.e., a variable-profile lens) is advantageous. For example, in the conventional variable focus lens described in Jpn. Pat. Appln. KOKOKU Publication No. 3-27090 (corresponding to Jpn. Pat. KOKAI Publication No. 60-114802), as the deformable member needs to be sealed in a container, there is a problem that assembly is complicated, and the lens is not suitable for miniaturization.
Moreover, for the above-described variable focus mirror of the fluid pressure system, because the mechanism is complicated, it is difficult to miniaturize the mirror, and there is a problem that the efficiency and response are deteriorated.
Furthermore, the above-described variable focus mirror of the fluid pressure system is applied particularly to the optics in which the light is obliquely incident. In this case, the aberration is generated in principle, and this may cause serious problems, depending on the use.
An object of the present invention is to provide a low-cost variable-profile optical device and optical element which have a quick response, and which can obtain a sufficient displacement with a small size.
Another object of the present invention is to provide a transmission-type variable-profile optical device and optical element which are small-sized and highly efficient.
A further object of the present invention is to provide a low-cost variable-profile mirror and variable-profile optical element which has a quick response, and which can obtain a sufficient displacement with a small size.
Another object of the present invention is to provide large-displacement variable-profile optical device in which fluid pressure is used, and a composite variable-profile optical element in which aberration correction is also achieved.
To achieve the above-described objects, according to a first aspect of the present invention, there is provided a variable-profile optical device comprising:
a light-transmission elastic member in which an elasticity of a first surface is set to be higher than that of a second surface disposed opposite the first surface,
wherein a pressure is applied to the second surface of the elastic member, so that the second surface of the elastic member is selectively deformed, and a focus distance may be varied.
To achieve the objects, according to a second aspect of the present invention, there is provided a variable-profile optical device comprising:
a light-transmission elastic member; and
a transparent rigid member bonded to a first surface of the elastic member,
wherein a pressure is applied to a second surface disposed opposite the first surface of the elastic member, so that the second surface of the elastic member is selectively deformed, and a focus distance may be varied.
To achieve the objects, according to a third aspect of the present invention, there is provided an optical element comprising:
a variable-profile optical device in which a pressure is applied to an elastic portion, a profile of the elastic portion is thereby changed and a focus distance may be varied;
a structural member which is bonded to a portion of the variable-profile optical device, and which supports the variable-profile optical device;
a pressure chamber bonded to the elastic portion of the variable-profile optical device, so that the pressure is applied to the elastic portion of the variable-profile optical device;
a pump device including a chamber, a diaphragm which also serves as a portion of a wall of the chamber, and nozzles for suction and discharge which are connected to the chamber; and
a vibration device which vibrates the diaphragm of the pump device,
wherein the pump device is connected to the pressure chamber and the outside of the structural member, at least a portion of the pressure chamber and a portion of the chamber of the pump device are disposed in the same structural member, and a vibration frequency or amplitude of the vibration device is controlled, so that a focus distance of the variable-profile optical device may be varied.
To achieve the objects, according to a fourth aspect of the present invention, the optical element according to the third aspect further comprises: a mark for optical axis adjustment in a visible portion of the structural member.
To achieve the objects, according to a fifth aspect of the present invention, there is provided the optical element according to the third or fourth aspect wherein the variable-profile optical device has light transmission properties,
the first surface has rigidity, and
the second surface disposed opposite the first surface has an elasticity lower than that of the first surface, and the second surface constitutes a variable-profile lens as the elastic portion to which the pressure is to be applied.
To achieve the objects, according to a sixth aspect of the present invention, there is provided the optical element according to the third or fourth aspect wherein the variable-profile optical device comprises a flexible thin film having at least a reflective surface in the first surface, and
a second surface of the flexible thin film constitutes a variable-profile mirror as the elastic portion to which the pressure is to be applied.
To achieve the objects, according to a seventh aspect of the present invention, there is provided the optical element according to the third or fourth aspect, further comprising: a plurality of the pump device; and a plurality of the vibration device,
wherein at least one of the pump device is connected in such a manner that the pressure chamber is pressurized, and at least one of the other pump device is connected in such a manner that the pressure of the pressure chamber is reduced, and
respective chambers of the plurality of the pump device are arranged via a line crossing at right angles to an optical axis of the variable-profile optical device.
To achieve the objects, according to an eighth aspect of the present invention, there is provided the optical element according to the seventh aspect, which stops the vibration device of the pump device for pressurizing or the vibration device of the pump device for pressure reduction, and controls the pressure of the pressure chamber to a desired value.
To achieve the objects, according to a ninth aspect of the present invention, there is provided a variable-profile mirror comprising:
a flexible thin film having an optical reflective surface;
a frame member which supports the flexible thin film;
a substrate which is disposed opposite to the flexible thin film, and which is bonded to the frame member;
a pressure chamber which includes a space surrounded by the flexible thin film and the substrate, and in which the flexible thin film and the substrate form a portion of a wall;
a pump device which is disposed opposite to the pressure chamber via the substrate, and which is bonded to the substrate;
a first channel which extends through the substrate, and which connects the pressure chamber to the pump device; and
a second channel which connects the pump device to the outside,
wherein the pump device sucks or discharges fluid with respect to the pressure chamber through the first and second channels, and the profile of the flexible thin film may be varied.
Moreover, to achieve the objects, according to a tenth aspect of the present invention, there is provided the variable-profile mirror according to the ninth aspect, wherein sectional areas of the first and second channels in a direction vertical to a flow direction of the fluid flowing through the first and second channels by operation of the pump device are larger on a downstream side of the flow than on an upstream side, and
the pump device comprises:
a chamber connected to the first and second channels;
a diaphragm which also serves as a portion of the wall of the chamber; and
vibration device for vibrating the diaphragm.
To achieve the objects, according to an eleventh aspect of the present invention, there is provided the variable-profile mirror according to the tenth aspect wherein a resonance frequency of the diaphragm of the pump device is higher than a resonance frequency of the flexible thin film.
To achieve the objects, according to a twelfth aspect of the present invention, there is provided the variable-profile mirror according to the ninth aspect, further comprising: a plurality of the first and second channels; and a plurality of the pump device,
wherein at least one of the pump device is connected via the first channel in such a manner that the pressure chamber is pressurized, and connected to the outside via the second channel, and
at least one of the other pump device is connected via another one of the first channels in such a manner that the pressure of the pressure chamber is reduced, and connected to the outside via another one of the second channels.
To achieve the objects, according to a thirteenth aspect of the present invention, there is provided the variable-profile mirror according to the ninth aspect wherein the substrate comprises single-crystal silicon, and the first and second channels are opened by anisotropic etching from different surfaces of the substrate.
Moreover, to achieve the objects, according to a fourteenth aspect of the present invention, there is provided a variable-profile optical element comprising:
a pressure-type variable-profile mirror in which a pressure is applied to a flexible thin film having an optical reflective surface and a shape of the flexible thin film is controlled;
an electrostatic variable-profile mirror in which a voltage is applied to the flexible thin film having the optical reflective surface and the shape of the flexible thin film is controlled; and
light guiding device for guiding a reflected light from the pressure-type variable-profile mirror to the electrostatic variable-profile mirror, or guiding the reflected light from the electrostatic variable-profile mirror to the pressure-type variable-profile mirror.
Furthermore, to achieve the objects, according to a fifteenth aspect of the present invention, there is provided the variable-profile optical element according to the fourteenth aspect wherein the pressure-type variable-profile mirror comprises:
a frame member which supports the flexible thin film;
a substrate which is disposed opposite to the flexible thin film, and which is bonded to the frame member;
a pressure chamber which includes a space surrounded by the flexible thin film and the substrate, and in which the flexible thin film and the substrate form a portion of a wall;
a pump device which is disposed opposite the pressure chamber via the substrate, and which is bonded to the substrate;
a first channel which extends through the substrate, and which connects the pressure chamber to the pump device; and
a second channel which connects the pump device to the outside,
wherein the pump device sucks or discharges fluid with respect to the pressure chamber through the first and second channels and a profile of the flexible thin film may be varied.
Additionally, to achieve the objects, according to a sixteenth aspect of the present invention, there is provided the variable-profile optical element according to the fifteenth aspect wherein sectional areas of the first and second channels in a direction vertical to a flow direction of the fluid flowing through the first and second channels by operation of the pump device are larger on a downstream side of the flow than on an upstream side, and the pump device comprises:
a chamber connected to the first and second channels;
a diaphragm which also serves as a portion of the wall of the chamber; and
a vibration device which vibrates the diaphragm.
Moreover, to achieve the objects, according to a seventeenth aspect of the present invention, there is provided the variable-profile optical element according to the sixteenth aspect wherein a resonance frequency of the diaphragm of the pump device is higher than a resonance frequency of the flexible thin film.
Furthermore, to achieve the objects, according to an eighteenth aspect of the present invention, there is provided the variable-profile optical element according to the fifteenth aspect, further comprising: a plurality of the first and second channels; and a plurality of the pump device,
wherein at least one of the pump device is connected via the first channel in such a manner that the pressure chamber is pressurized, and connected to the outside via the second channel, and
at least one of the other pump device is connected via another one of the first channels in such a manner that the pressure of the pressure chamber is reduced, and connected to the outside via another one of the second channels.
Additionally, to achieve the objects, according to a nineteenth aspect of the present invention, there is provided the variable-profile optical element according to the fifteenth aspect wherein the substrate comprises single-crystal silicon, and the first and second channels are opened by anisotropic etching from different surfaces of the substrate.
Moreover, to achieve the objects, according to a twentieth aspect of the present invention, there is provided the variable-profile optical element according to the fourteenth aspect wherein the electrostatic variable-profile mirror comprises:
an electrode disposed on a back surface of the optical reflective surface of the flexible thin film;
a frame member which supports the flexible thin film;
a substrate which is disposed opposite to the flexible thin film, and which is bonded to the frame member; and
a plurality of electrodes disposed opposite to the flexible thin film on the substrate surface.
Furthermore, to achieve the object, according to a twenty-first aspect of the present invention, there is provided the variable-profile optical element according to the twentieth aspect wherein a voltage correlated with a deformed amount of the pressure-type variable-profile mirror is selectively applied to the plurality of electrodes on the substrate so as to correct an aberration generated by the reflected light from the pressure-type variable-profile mirror having the flexible thin film deformed by the pressure applied to the flexible thin film of the pressure-type variable-profile mirror.
Additionally, technical terms for use in the above-described constitution and the present specification are based on the following definitions.
Variable-profile optical device: an optical device having a profile controlled by a pressure, electrostatic force, and the like, so that the focus distance may be varied.
Diaphragm: a vibrating thin film, diaphragm.
Pressure chamber: a space in which the pressure is applied to the elastic portion of the variable-profile optical device.
Micro electromechanical system (MEMS): a micro machine in which a semiconductor manufacturing process is used.
Chamber for exhaust: a chamber of an exhaust pump from the pressure chamber, including the diaphragm.
Chamber for suction: a chamber of a suction pump to the pressure chamber, including the diaphragm.
Chamber: a pressure chamber of the pump, including the diaphragm.
Nozzle: the nozzle connects the chamber to the pressure chamber or the outside, forms the channel of the fluid, and has different sectional areas on a chamber side and an opposite side.
Mark: a mark for matching/adjusting the optical axis of the optical device.
Channel: the channel includes the first channel for connecting the pressure chamber to the pump device, and the second channel for connecting the pump device to the outside, forms the channel of the fluid, and has different sectional areas on the pressure chamber side and the opposite side.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by device of the instrumentalities and combinations particularly pointed out hereinafter.